In chromatographic applications, for example in liquid chromatography, it is necessary for a wide variety of purposes to couple liquid-carrying capillaries or else optical waveguides to chromatographic components, such as chromatography columns or sensors. Connection devices or connection components of various embodiments are used for this. The connection components, in particular socket or plug devices, may also be releasably or unreleasably connected to the chromatography component concerned and form a constituent part of the component.
In all of these applications it is necessary to connect the connection component or the fluid capillary that is releasably or unreleasably connected to the connection component, or the optical waveguide connected thereto, fluid-tightly to the respective chromatography component. The fluid capillary to be connected or the optical waveguide to be connected or any other component that is to be respectively connected fluid-tightly to a chromatography component is referred to hereinafter as the insert, which is coupled to the chromatography component by means of a connection component (which may also consist of multiple individual parts).
In this respect, WO 2011/079058 A1 discloses for example a fluidic connection device in which an optical waveguide in the form of an optical fiber is fixed by means of clamping parts in a main body that has an axial bore in such a way that it passes through the axial bore. In the front region, the aperture in the main body is of a conically tapering form. A plastically deformable plastic part with a central bore through which the optical fiber to be fixed protrudes is inserted into this conical taper. The plastic part is likewise formed in a complementarily conical form in its front region and is axially acted upon on its rear side by a further hollow-cylindrical clamping part. This further hollow-cylindrical clamping part is connected to the main body in the form of an interference fit during an axial pressing-in process and acts upon the front conical clamping part. In the pressing-in process, the front conical clamping part is axially acted upon by the hollow-cylindrical clamping part and pressed into the conical region of the main body with such a great force that a fluidically tight connection and simultaneous fixing of the optical fiber in the main body are obtained. In the final state, the optical fiber may finish flush with the end face of the main body or protrude from it, possibly together with an un-formed front region of the conical clamping part.
Disadvantages of this are the use of multiple clamping parts and the use of an interference fit for the hollow-cylindrical clamping part, with the result that it is only with difficulty that a defined axial force can be applied to the front, conical clamping part for pressing it into the conical region of the main body.
Furthermore, WO 2007/009493 A1 discloses a coupling device in which a chromatography component, such as a chromatography column, already has a socket-like unit, into which a fluid-carrying capillary can be inserted. The socket unit has a projecting cylindrical region, onto which a hollow-cylindrical part can be mounted, the hollow-cylindrical part also encompassing with its rearward region the end face of the hollow-cylindrical region of the socket. After being mounted onto the hollow-cylindrical region of the socket, the hollow-cylindrical part, which consists of a thermoplastic material, is shaped by means of a mold in such a way that a radially inwardly directed pressure is obtained and, moreover, the rearward region of the hollow-cylindrical, shaped part finishes flush with the outer circumference of the inserted capillary and becomes connected to it. The plastic shaping process consequently produces a fluid-tight connection. At the same time, during the cooling of the shaped hollow-cylindrical connection part there is the additional effect that, as a result of the greater coefficient of thermal expansion of this thermoplastic material in comparison with the material of the fluid-carrying capillary, an even greater radially inwardly directed pressure, and consequently corresponding holding forces, are exerted on the capillary.
A disadvantage of this, however, is that such a connection of a capillary to a chromatography component no longer allows the capillary to be released. Moreover, the thermal shaping of the hollow-cylindrical connection part under pressure requires a corresponding amount of effort. In addition, the melting of at least partial regions of the prefabricated component may cause problems with the dimensional stability of the finished component produced, since the prefabricated part may be deformed by the melting process.